That's a quarter of the circle. So find the area of the circle, and divide by 4 to get the answer.
Circle area = 3.14*13^2 = 530.66
Answer = circle area / 4 = 132.665
(a-25b)(a+4b)=0
Use the quadratic formula or complete the square by looking at the factors
It would be right-angled Triangle.
You can check for that, by putting the values into Pythagoras Theorem:
H² = P² + B²
10² = 8² + 6²
100 = 64 + 36
100 = 100
L.H.S = R.H.S
As it obeys Pythagoras theorem, It would be a right-angled triangle only, with two small arms (Base & Perpendicular) and a long arm, opposite to perpendicular (Hypotenuse)!!!
Hope it helped.